The present invention relates to an exhaust energy recovery apparatus for an engine mounted on a motor vehicle and, more particularly to an exhaust energy recovery apparatus for an engine, including a turbine disposed in an exhaust system of the engine and drivable with maximum efficiency.
There have been developed in recent years ceramic internal combustion engines having various components made of ceramic. Since the ceramic engines are not required to be cooled, it is expected to increase the thermal efficiency of these engines by recovery the energy of high-temperature exhaust gases from the engines and feeding the recovered energy back to the drive power transmitting system.
One conventional exhaust energy recovery engine which has been developed is a so-called turbocompound engine including a turbine disposed in an engine exhaust system for producing rotative power which is directly fed back to the output shaft of the engine through a speed reducer. The turbocompound engine is however disadvantageous in that it requires a speed reducer of a very high speed reduction ratio capable of matching the high rotational speed of the turbine with the rotational speed of the engine, and that the entire apparatus is large in size and the power transmission efficiency is low.
In view of the aforesaid drawbacks, the inventors have developed an exhaust energy recovery apparatus for an engine, which, rather than feeding the rotative drive power of a turbine directly back to the output shaft of the engine through a mechanical mechanism, drives a generator with the turbine and supplies generated electric power to a motor in the power transmitting system of the engine so as to feed back the generated power as drive power. Such a developed apparatus is disclosed in Japanese Laid-Open Publication No. 58-214615, for example.
The foregoing exhaust energy recovery apparatus for an engine is however arranged to operate without checking output conditions of the engine which vary at all times dependent on the running conditions of the motor vehicle. Therefore, the earlier exhaust energy recovery apparatus is not designed to operate the turbine with best efficiency at all times.